BORNEO'S dense, virgin rainforests are interspersed with large, naked patches where trees have been plucked out by loggers. Meandering rivers such as the Baram that run through the forests have turned red with silt washed down from the now-barren hillsides.

The government and the timber companies, however, blame tribal shifting cultivators, about 200,000 of whom live in Sarawak, for these adverse effects. But it is modern civilisation's demand for wood that has spelt doom for 25,000 sq km of Sarawak's remaining rainforests. Sarawak is the largest source of unprocessed tropical timber, with Japan buying about two-thirds of the output of 15 million cubic metres of timber.

Roughly half of Sarawak's concessions are on state land, where the felling of all trees is allowed. In the remaining, so-called protected forests, the aim is to manage the forest sustainably by selective logging.

But, according to S C Chin of the University of Malaysia, logging is not scientifically planned nor is it properly supervised. "Several studies have shown that removing six to 12 trees per ha also destroys about 70 other trees in the process," says Chin. "These trees are torn down to clear a path out for the harvested trees. As a result, about 40 per cent of the logged forest becomes open space."

The heavy machinery used churns up the exposed soils, compacts them and makes them impermeable. This, coupled with the loss of tree canopy that protects the forest floor from rainfall, causes waterlogging and severe soil erosion. According to the Malaysian government, most of Sarawak's rivers now suffer from excess sediment -- "soil pollution". The water becomes turbid and fish stocks, the main source of protein for forest-dwellers, dwindle.

Chin, who spent 15 years researching shifting cultivation, estimates a typical tribal family clears only 2 ha of forests a year -- a total of 72,000 ha per annum. This is small compared to the 500,000 ha logged by timber companies every year. And, according to Chin, only 5 per cent of the land cleared by shifting cultivators is virgin forest.